For the cardiac event cases patients are selected from the Brigham and Women's Hospital cardiac services at the time of discharge, aged 45-74, having suffered a cardiac event resulting in either an infarct or need for a cardiac procedure (angioplasty, stint, etc). For the CHF patients they are selected from the BWH cardiac clinics where they have been identified and classified as stage 3 or 4 CHF. For both groups residence requirements are that they reside within the Greater Boston Area as defined by an outer ring road (Route 495) and are willing to be visited at home and have the exposure assessment equipment set up in their home as well as be monitored personally.